Atherosclerosis is the principal cause of myocardial infarction, stroke, and peripheral vascular disease, accounting for nearly half of all mortality in developed countries. Percutaneous transluminal angioplasty has become a well-established technique for revascularization of occluded arteries. However, the long-term efficacy of the procedure remains limited by progressive vessel renarrowing (restenosis) within the following few months after angioplasty. Abnormal vascular smooth muscle cell (VSMC) proliferation and migration is thought to play an important role in the pathogenesis of both atherosclerosis and restenosis. The stimulation of VSMC proliferation and migration requires signals arising from both growth factors and the extracellular matrix (ECM). The focal adhesion kinase family of nonreceptor protein tyrosine kinases (PTKs) - focal adhesion kinase (FAK) and proline-rich tyrosine kinase-2 (PYK2) - play a central role in modulating VSMC signal transduction. The overall goal of this research project is to develop novel approaches in treatment of vascular injury following balloon angioplasty. The overall hypothesis of my NRSA application is that upregulation of FRNK, a naturally occurring inhibitor of FAK and PYK2, during vascular remodeling reduces smooth muscle cell migration and proliferation, and this occurs via multiple mechanisms. In Specific Aim 1, I will examine the temporal relationship between FAK, PYK2 and endogenous FRNK expression following balloon angioplasty. In Specific Aim 2, I will use adenoviral-mediated gene transfer to overexpress and knock down FRNK following balloon injury of the rat carotid artery, and analyze their effects on VSMC migration and proliferation in the arterial wall as well as analyze FAK and PYK2-mediated signal transduction. In Specific Aim 3, I will examine the role of FRNK localization and FRNK tyrosine phosphorylation in the inhibition of FAK and/or PYK2- dependent signaling, and FRNK's independent signaling function as compared to cells depleted of FAK. I believe that the questions addressed by this project have fundamental importance to our understanding of VSMC signaling. Future therapies for vascular remodeling in arterial diseases may include regulation of VSMC FRNK expression to selectively limit VSMC migration and proliferation without inhibition of beneficial endothelial function.